Every commercial shipment that enters or leaves Mexico is cleared by an electronic customs declaration called the pedimento. It is filed through Mexico's customs system under the importer's or exporter's tax identity, usually by a licensed customs broker (agente aduanal), and it is the document that fixes the customs regime, the tariff classification, the declared value and the duties and taxes due. IMMEX is a separate, government-authorised program that lets manufacturers and service exporters bring in inputs and equipment under a temporary regime, without paying import duty up front, on condition that the finished goods are exported. Two things in this area are widely misunderstood: a customs broker is not mandatory in every case, and 2026 brought real changes to both the customs law and the import tariff. This guide covers the mechanics and flags what changed, with as-of dates. For the shipping side of the same corridor, see our Mexico to USA shipping guide.
What the pedimento is and what it does
Article 36 of the Ley Aduanera (the Mexican Customs Law) requires anyone who brings goods into Mexico or takes them out under a customs regime to file a pedimento through the electronic customs system, in the form the tax authority prescribes. The declaration is signed electronically and, with the goods, goes through the automated selection mechanism at the customs facility, the "red light, green light" step that decides whether the shipment is released or inspected.
The pedimento carries a two-character regime key. Three you will see often are A1 (definitive import or export), IN (temporary import of inputs, the usual key for IMMEX) and RT (return of goods). The full list sits in the annexes to the General Foreign Trade Rules (RGCE), so treat these three as examples, not a complete table. A pedimento is not a one-off form that disappears after release: the law requires an electronic file for each operation, covered below.
Who files it: customs broker, customs agency or your own representative
A common claim is that Mexico requires a licensed customs broker for every import. That is not what Article 40 of the Ley Aduanera says. Customs clearance may be promoted by the importer or exporter directly, or through a customs broker or customs agency. A company that clears goods without a broker must do it through a legal representative who meets conditions in the law: Mexican nationality, being current on tax obligations, an employment relationship with the company and demonstrated foreign trade knowledge or experience. As the tax authority's own registry procedures put it, an applicant designates a customs agent, a customs representative or a legal representative. (Article 40 is not among the articles amended by the November 2025 reform decree.)
In practice, most small and mid-sized shippers and nearly all one-off importers use a broker, because the broker holds a licence (a patente) from the tax authority and carries legal responsibility the importer would otherwise carry alone. Under Article 54, the broker or agency is responsible for the accuracy of the data supplied, for correct payment of duties, for determining the customs regime, for correct tariff classification and for the correct commercial identification number. The broker must also make sure the importer has the documents proving compliance with foreign trade and non-tariff regulations. Article 53 makes brokers jointly liable for taxes arising from the operations they handle. That is why a good broker will refuse to file on thin paperwork.
Foreign shippers should note the practical consequence: the importer of record on the Mexican side is a Mexican taxpayer, not the overseas seller. If you are an exporter selling delivered duty paid into Mexico, someone in Mexico still has to hold the tax registration and answer for the pedimento. For the parallel US question, see do you need a customs broker.
The importer registry and the sector registry
Article 59, section IV of the Ley Aduanera obliges importers to be listed in the Padron de Importadores and, where relevant, in the Padron de Importadores de Sectores Especificos. The tax authority (SAT) describes the sector registry as the one a company must join before importing goods in certain regulated tariff headings. Its procedure page lists 16 sectors, including chemicals, firearms and explosives, textiles, footwear, alcohol, hydrocarbons, steel products and automotive goods. Requirements it states include:
- An active tax registration (RFC) and a valid electronic signature (e.firma).
- Current tax compliance, with the company absent from SAT's published lists of non-compliant taxpayers.
- A registered fiscal address and a validated tax mailbox.
- A designated customs agent, customs representative or legal representative.
SAT commits to a response within ten business days. One caution: the procedure page still points to an older edition of the annex that lists the covered tariff headings, so confirm the current annex to the RGCE before assuming a product is in or out. A new importer that discovers this on the day a container arrives is the usual cause of demurrage and storage charges, so check registration before booking.
IMMEX: temporary import for manufacturing and export
IMMEX (Industria Manufacturera, Maquiladora y de Servicios de Exportacion) is a program authorised by the Secretaria de Economia under a decree first published on 1 November 2006. An authorised company can import inputs, parts, packaging and certain equipment temporarily, without paying the general import duty, on the basis that the output is exported. The program has several modalities (industrial, services, parent-company, shelter and outsourcing, according to current descriptions), and the shelter model lets a foreign manufacturer operate in Mexico under a host company's program.
The customs-law side sits in Article 108 of the Ley Aduanera. As the article stands in the text we checked (a 2026 compilation of the law), raw materials, parts and components, process fuels and lubricants, and packaging may stay up to 18 months, counted from the pedimento date, within which they must be returned abroad or moved to another regime. Machinery, equipment and tools may stay for the life of the program. The November 2025 customs reform did amend the last paragraph of Article 108: after a program is cancelled, the company must convert the goods to definitive import or return them within 60 calendar days of notification. The decree leaves the rest of Article 108 as it was, so the 18-month periods stand, but confirm the current wording with your broker rather than relying on a compilation.
Two further points matter to anyone moving goods for an IMMEX operator. First, import duty suspension is not the same as VAT treatment: whether the operator pays VAT on temporary imports and recovers it, or is exempt through a certification, depends on the company's authorisations, so ask the operator's tax adviser. Second, the program carries a list of goods that cannot be imported under it. A law-firm summary reports that finished footwear (headings 64.01 to 64.05) was added to that list in a decree published on 28 August 2025, on top of earlier restrictions on goods such as sugar, alcohol, textiles and apparel. Treat that as a lead to check against the decree itself, not as a settled list.
IMMEX compared with a normal import, duty drawback and inward processing
| Question | Normal (definitive) import | IMMEX temporary import | US duty drawback |
|---|---|---|---|
| When is duty paid? | At import | Not paid on the inputs at import, if the conditions are met | Paid at import, partly refunded later |
| What triggers relief? | Nothing | Authorised program plus export or return of output within the time limit | Export or destruction of the imported or substituted goods |
| Who authorises it? | No authorisation beyond registries | Secretaria de Economia program, with customs obligations enforced by SAT | US Customs and Border Protection claim |
| Main risk | Wrong classification or value | Missing the return deadline, inventory-control gaps, goods that cannot be imported under the program | Missing records or the filing deadline |
The closest comparison in other systems is inward processing, covered in our guide to inward and outward processing relief: duty is suspended up front, and it becomes payable if the conditions are not met. US duty drawback works the other way around, refunding duty after the fact. If you want a one-line rule: IMMEX suspends, drawback refunds.
What changed for 2026
These are the changes we could confirm, with the source. As of 6 October 2026:
| Change | What it says | Source and date |
|---|---|---|
| Customs law reform | More than 100 articles of the Ley Aduanera amended; mostly in force 1 January 2026, with a few provisions starting one and three months later | Decree in the Diario Oficial (DOF), 19 November 2025 |
| Electronic file | Each customs operation needs an electronic file that includes the digital invoices, commercial invoices, payment proof, transport and insurance costs, contracts and support for value adjustments, among other records | Article 59 as amended, same decree |
| Broker licences | Existing patents and agency authorisations run for 20 years, renewable, with a new Customs Council (Consejo Aduanero) deciding on grants, suspensions and cancellations | Fourth transitory provision and Article 159 bis, same decree |
| Regulations | The decree ordered the implementing regulations to be reformed within 120 days; reported as published 23 February 2026 | Decree for the order; law-firm and customs-broker association notices for the date |
| General import tariff | New general rates of 5 percent to 50 percent on roughly 1,400 to 1,500 tariff lines (law-firm counts vary), mainly textiles, footwear, steel, aluminium, plastics and automotive goods; in force 1 January 2026 | DOF decree published 29 December 2025 |
| Second tariff decree | Further changes to 185 tariff lines, with some steel lines at exempt rates for specific PROSEC sectors; in force the day after publication | DOF, 23 April 2026 (reported by a customs consultancy and a law firm) |
A few things about the tariff decree are easy to get wrong. The 29 December 2025 decree raises the general rates in the tariff schedule. It does not list countries. In its fourth transitory provision it also says the Secretaria de Economia may set up specific mechanisms to secure the supply of inputs from countries with which Mexico has no free trade agreement in force. Law-firm summaries describe the practical effect as hitting goods from non-treaty origins such as China, while goods that qualify for a preference under a treaty keep that treaty's rate if the origin documents are in order. Do not assume every Asian origin is affected: Mexico has trade agreements with several Asian economies (Japan, and the CPTPP members, for example), subject to each treaty's own rules, so check origin by origin on the Secretaria de Economia treaty list. Importers who operate under IMMEX or PROSEC should also ask their adviser how the new rates interact with their programs, because one law-firm advisory we read told readers to check that point against the final decree text.
We did not rely on several widely repeated claims that come only from vendor blogs, such as specific new annual-report deadlines for IMMEX or new fine ceilings in the customs law. If one matters to you, ask your broker for the decree article.
Carta Porte: the domestic leg inside Mexico
Once goods are cleared, moving them by road, rail, air or sea inside Mexico needs an electronic invoice (CFDI) with the Carta Porte complement. SAT's own page says general use became obligatory on 1 January 2022, that for foreign trade operations the invoice with Carta Porte is required from 1 January 2024, and that since 17 July 2024 only CFDI version 4.0 with Carta Porte complement version 3.1 is valid. SAT's guidance for imports and exports says the Carta Porte must exist before the goods go through the automated selection mechanism, with exceptions for foreign carriers without a permanent establishment in Mexico and for goods under pedimento key V1. SAT updates this complement often, so confirm the current version on its Carta Porte page before building it into a booking process. A missing or wrong Carta Porte is a classic reason a truck is held at a checkpoint.
USMCA origin: what the certification needs
If the goods claim USMCA (called T-MEC in Mexico) preferential treatment, Chapter 5 of the agreement sets the rules, and they are short. The certification of origin need not follow a prescribed format, but must carry the minimum data elements in Annex 5-A. It may be completed by the exporter, the producer or the importer, may sit on an invoice or any document, and may be in English, French or Spanish. It can cover a single shipment or multiple identical shipments over up to 12 months. The importing country's customs authority must accept a certification for four years after it was completed. The importer must hold a valid certification when it makes the claim, and must keep the records for at least five years from the date of import (Article 5.8). Under Article 5.5 no certification is required for importations not exceeding US$1,000, though each country may set a higher figure and may require a written statement.
The origin rules themselves, such as tariff-shift tests and regional value content, are a different subject; see rules of origin and preferential duty and free trade agreement certificates of origin. As of 1 July 2026, reports from law firms and trade press say the three countries held the agreement's first joint review and the United States did not agree to a 16-year extension, which leaves the agreement in force until 1 July 2036 with annual reviews. We have not confirmed this from the trade ministries, so read it as context, not a rule change, and check the official notices if you plan long-term contracts around it.
The handoff to a US entry
Goods leaving Mexico for the US are exported under a Mexican export pedimento, then entered into the US by the importer of record or its licensed US customs broker. A frequent confusion is the Importer Security Filing (ISF, "10+2"). Under 19 CFR 149.2 it applies to cargo arriving in the US by vessel, with filing due 24 hours before the cargo is loaded at the foreign port. It does not apply to a truck crossing the border at Laredo or a rail car at Eagle Pass.
For trucks, the carrier must transmit advance electronic cargo information through the CBP-approved system, typically no later than one hour before arrival at the first US port (30 minutes for FAST-qualified shipments), under 19 CFR 123.92. The US importer or its broker may supply part of the data under the dual-party arrangement. The US entry itself still needs a customs bond, the right classification and value, and any agency requirements, as in our Mexico to USA guide. US tariff treatment of Mexican goods has changed repeatedly in 2025 and 2026, so check CBP's current messages before quoting landed cost.
Common mistakes on the Mexican side
- Assuming a broker is mandatory, or that a broker removes your risk. A broker is responsible for the filing, but the importer still owns the records and the origin or value claims.
- Not checking the sector registry. Goods in a regulated sector without the registration are stopped at the border.
- Treating IMMEX as permanent duty-free status. It is a temporary regime with a return deadline and inventory control.
- Using a generic origin certificate. A T-MEC claim needs the Annex 5-A data and a certifier who can back it up.
- Quoting 2025 duty rates. Rates for many non-treaty origins changed on 1 January 2026 and again for some lines on 24 April 2026.
What to do next
- Confirm who will be the importer or exporter of record in Mexico and whether that company is in the Padron de Importadores (and the sector registry, if the goods require it).
- Get the tariff classification and the current general rate from a Mexican customs broker, not from a 2025 rate sheet, and check whether the goods can claim a treaty preference.
- If a manufacturer is involved, ask whether it holds an IMMEX program and what its return deadlines are.
- Set up the origin certification and the Carta Porte before the truck is booked, then agree who files the US entry and ACE manifest.
If you need a Mexican customs broker, forwarder or trucking company, more than 29,300 logistics companies are searchable by country and service in the CargoLinked directory, and the public requests board lists freight that shippers have posted for forwarders to quote on directly: see open requests.
This article is general information, not legal, tax or customs advice. Mexican customs rules change often, and some details above rest on law-firm summaries rather than the primary text. Confirm anything that affects a shipment with the Servicio de Administracion Tributaria, the Agencia Nacional de Aduanas de Mexico, the Diario Oficial de la Federacion, or a licensed customs broker.
